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United States Patent |
5,762,067
|
Dunham
,   et al.
|
June 9, 1998
|
Ultrasonic endoscopic probe
Abstract
An ultrasonic endoscopic probe is provided with an articulating distal tip
at which and ultrasonic transducer is located. The articulating section of
the probe can be locked in an articulated position by a lock control
located at a control section of the probe. The locking force is variably
selectable by the user, so that the articulating section will be locked in
position by a desired force. The articulating section is controlled by
cables, which include cable tension adjustments that also serve to delimit
the range of articulation. The articulating section is formed of
alternating pivot rings with intervening polymeric pivot beads, which
provide repetitively smooth articulation. The ultrasonic transducer is
rotatable to steer the acoustic scan plane during use, and a sliding
membrane between the transducer and its acoustic window allows the
transducer to rotate smoothly without sticking.
Inventors:
|
Dunham; Paul T. (Everett, WA);
Brechbiel; Tracy C. (Lake Stevens, WA);
Zimmerman; Calvin R. (Burnham, PA);
Oaks; Frank Bentley (Renton, WA)
|
Assignee:
|
Advanced Technology Laboratories, Inc. (Bothell, WA)
|
Appl. No.:
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655393 |
Filed:
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May 30, 1996 |
Current U.S. Class: |
600/462; 600/148 |
Intern'l Class: |
A61B 008/12; A61B 001/00 |
Field of Search: |
128/660.1,662.06
600/146-152,141,142
|
References Cited
U.S. Patent Documents
3557780 | Jan., 1971 | Sato | 600/148.
|
3948251 | Apr., 1976 | Hosono | 128/4.
|
4078555 | Mar., 1978 | Takahashi | 600/148.
|
4919112 | Apr., 1990 | Siegmund | 128/4.
|
4932394 | Jun., 1990 | Nanaumi | 600/148.
|
4996975 | Mar., 1991 | Nakamura | 128/6.
|
5014685 | May., 1991 | Takahashi | 128/4.
|
5018506 | May., 1991 | Danna et al. | 128/4.
|
5179935 | Jan., 1993 | Miyagi | 128/4.
|
5299559 | Apr., 1994 | Bruce et al. | 128/4.
|
5402793 | Apr., 1995 | Gruner et al. | 128/660.
|
5512035 | Apr., 1996 | Konstorum et al. | 600/146.
|
Primary Examiner: Jaworski; Francis
Attorney, Agent or Firm: Yorks, Jr.; W. Brinton
Claims
What is claimed is:
1. An ultrasonic endoscopic probe including a control section and an
articulating distal end at which an ultrasonic transducer is located,
comprising:
a user adjustable control mechanism, located at said control section and
coupled to said distal end, for adjusting the articulation of said distal
end;
a braking mechanism, located at said control section and coupled to said
control mechanism, for applying a braking force to said control mechanism
to lock said articulating distal end in an articulating condition; and
wherein said braking mechanism further includes means for setting said
braking mechanism to apply one of a plurality of different user selectable
degrees of braking force to said control mechanism.
2. The ultrasonic endoscopic probe of claim 1, wherein said means for
setting said braking mechanism to apply one of a plurality of different
user selectable degrees of braking force comprises means for setting a
braking force from among a continuously variable range of braking forces.
3. The ultrasonic endoscopic probe of claim 2, wherein said means for
setting a braking force from among a continuously variable range of
braking forces includes a thumbwheel control.
4. The ultrasonic endoscopic probe of claim 1, wherein said means for
setting said braking mechanism to apply one of a plurality of different
user selectable degrees of braking force comprises means for setting said
braking mechanism to apply one of a finite number of discrete braking
forces.
5. The ultrasonic endoscopic probe of claim 4, wherein said means for
setting said braking mechanism to apply one of a finite number of discrete
braking forces includes a detent mechanism.
6. The ultrasonic endoscopic probe of claim 5, wherein said detent
mechanism includes a plurality of cam surfaces.
7. The ultrasonic endoscopic probe of claim 6, wherein said detent
mechanism includes a step cam.
8. The ultrasonic endoscopic probe of claim 6, wherein said detent
mechanism further includes a cam follower which is adjustable by the user
to ride on one of said cam surfaces for setting said braking mechanism to
apply one of a finite number of discrete braking forces.
9. The ultrasonic endoscopic probe of claim 8, wherein said cam follower is
pivotably mounted to apply different degrees of braking forces to said
control mechanism when riding on different ones of said cam surfaces.
10. The ultrasonic endoscopic probe of claim 1, further comprising a
warning indicator, coupled to said braking mechanism, for providing an
indication when said articulating distal end is locked.
11. An ultrasonic endoscopic probe including a control section and an
articulating distal end at which an ultrasonic transducer is located,
comprising:
a user adjustable control mechanism, coupled to said distal end, and
including a metallic rotating member for adjusting the articulation of
said distal end;
a braking mechanism, located at said control section and coupled to said
control mechanism, for applying a braking force to said metallic rotating
member of said control mechanism to lock said articulating distal end in
an articulating condition,
wherein said braking mechanism includes a surface contacting said rotating
member which is made of a polymeric material to prevent seizing of said
rotating member when engaged with a braking force.
Description
This invention relates to ultrasonic endoscopic probes by which an
ultrasonic transducer located at the distal tip of an endoscope is
manipulated while located within the body from an external control unit.
U.S. Pat. No. 5,479,930 describes an ultrasonic endoscopic probe with an
ultrasonic transducer at the distal tip of the probe. The distal tip
includes an articulation section which is capable of being articulated in
up-down and left-right directions so that the transducer may be remotely
moved and aimed at a region of the body which the user desires to image.
Once the user has articulated the distal tip with its transducer in the
desired manner the articulation section may be locked in its articulated
position while the user views ultrasonic images produced from echoes
received by the transducer.
In accordance with the principles of the present invention, an improved
ultrasonic endoscopic probe is provided which includes a variable force
locking mechanism. The articulating section of the distal tip may be
locked in a desired position with variable locking forces. The variable
locking forces permit the articulating section to yield in response to
movement of the body so as to prevent injury when a patient moves, or the
probe is accidentally withdrawn from a body cavity of a patient when
locked in an articulated position. The locking force is applied by means
of a braking surface of one material which engages a different material of
an articulation mechanism to prevent binding or seizing of the
articulation mechanism. The articulating section is articulated by a
control cable which includes a tension adjustment device. The tension
adjustment device also serves as a range limiter to limit the range of
articulation of the articulating section. The control cable passes through
a cable conduit, which is seated in a spring loaded mechanism which
absorbs forces which are suddenly applied to the articulating section. The
articulating section is formed of a plurality of pivot rings and pivot
beads. The rings and beads are made of metallic and polymeric material,
respectively, and include apertures which seat the beads in the rings, and
through which the control cable passes. The ultrasonic transducer at the
distal tip of the probe is rotatable and includes a sliding membrane
between the transducer and acoustic window to allow the transducer to
rotate smoothly without sticking or binding.
In the drawings:
FIG. 1 is a plan view of an endoscopic probe of the present invention;
FIG. 2 is a cross-sectional view of the articulation control system of the
probe of FIG. 1;
FIG. 3 illustrates the principle of the articulation locking mechanism of
an articulating probe;
FIG. 4 is a plan view of the variable force articulation locking mechanism
of the present invention;
FIG. 5a is a plan view of the handle of an endoscopic probe of the present
invention;
FIG. 5b is partial cutaway side view of the handle of FIG. 5a, showing the
cable guide strain relief and cable limit stop arrangements;
FIG. 6 is a cross sectional view of the sleeve for the cable guide strain
relief arrangement of FIG. 5;
FIGS. 7a and 7b are side and front views of one of the pivot rings of the
articulating section of the probe of FIG. 1;
FIG. 8 illustrates the articulating link assembly of the probe of FIG. 1;
FIG. 9 is an enlarged view of the articulating link assembly of FIG. 8; and
FIG. 10 illustrates the distal tip of the probe in which the ultrasonic
transducer is rotatably located.
Referring first to FIG. 1, a plan view of an ultrasonic endoscopic probe is
shown. The probe includes a handle 10 where the major controls of the
probe are located. Extending from one end of the handle 10 is an endoscope
tube 12. The endoscope tube is suitable for insertion into a body cavity
such as the esophagus, rectum, or through a surgical incision and can
range up to a length of 100 cm. At the end of the endoscope tube 12 is the
distal tip 14 of the probe where an ultrasonic transducer is located.
Extending from the other end of the handle 10 is an electrical cable 16
which terminates at a connector 18. The connector 18 is suitable for
connecting the probe to an ultrasound system which energizes the probe and
displays images formed from the acoustic signals transmitted and received
by the transducer at the tip of the probe.
Five of the probe controls are shown in FIG. 1. Two buttons 20 and 22
control selection of the image plane to be scanned by the transducer
within the probe tip. The probe tip is connected to the endoscope tube by
an articulating section 30 by which the tip can be articulated in any of
four directions from the handle by the left-right articulation control
knob 24 and the up-down articulation control knob 26. Reciprocating brake
buttons 28, 28' are used to lock and unlock the articulating section in
any articulated position.
Referring to FIG. 2, a cross-sectional view of the articulation control
system of the probe of FIG. 1 is shown. The left-right control knob 24 is
attached to one end of a shaft 32. A pulley 34 is connected to the other
end of the shaft 32 and is rotated by rotation of the control knob 24. As
the pulley is rotated, the cables 76,76' (not shown in this drawing) which
are wrapped around and attached to the two grooves of the pulley and
extend to the articulating section of the probe are reciprocated. The
reciprocation of the cable causes the distal tip 14 of the probe to
articulate to the left or the right, depending upon the direction in which
the knob 24 is turned.
The up-down control knob 26 is connected by screws 36 to an upper pulley
38. Both the knob 26 and the pulley 38 surround the shaft 32 of the
control knob 24 and operate independently therefrom. As the pulley 38 is
rotated, the cables 74,74' (not shown in this drawing) which are wrapped
around and attached to the two grooves of the pulley and extend to the
articulating section of the probe are reciprocated. The reciprocation of
this cable causes the distal tip 14 of the probe to articulate up or down,
depending upon the direction in which the knob 26 is turned.
The handle 10 also contains a locking mechanism by which the articulating
section 30 can be locked in a particular articulated or unarticulated
position. The principle of the locking mechanism is illustrated in FIG. 3,
in which an articulating mechanism pulley 128 and articulation control
cable 129 are locked in position by a brake pad 146a. The brake pad 146a
is seen to have a concave end surface which engages the circumference of
the pulley 128. The brake pad 146a is urged against the pulley 128 by
movement of the brake cam 140a, which moves in a reciprocating manner as
indicated by arrow 152. As the brake cam is moved to the upper left, a cam
follower 142a is depressed by surface 141 of the brake cam 140a. The cam
follower in turn compresses a spring 148a inside the body of the brake pad
146a, causing the brake pad to bear more forcefully against the
circumference of the pulley 128, thereby impeding its rotation and
articulation of the distal end of the probe.
Referring back to FIG. 2, the upper and lower pulleys 38 and 34 are engaged
by brake pads 146a and 146b, respectively. To avoid binding or seizing of
the lock mechanism due to a metal on metal contact, the concave surfaces
of the brake pads are lined with a layer of a polymeric material. This
enables the pulleys to be turned smoothly when engaged lightly by the
brake pads. Apertures are located in the sides of the brake pads opposite
the concave surfaces. Each aperture is engaged by a push rod 40a, 40b.
Each push rod has a flange surface 41a, 41b which compresses a spring 48a,
48b against the brake pad.
The push rods are urged against the brake pads and springs by a pair of
pivoting rockers. A long rocker 50a is pivotally connected at a pivot
point 52a to push rod 40a. A short rocker 50b is pivotally connected at a
pivot point 52b to push rod 40b. The long rocker 50a has a rocker arm 54a
which rides on the cam surface of a step cam 56a. The short rocker 50b has
a rocker arm 54b which rides on the cam surface of a step cam 56b. Both
rockers pivot about a common pivot point 51, chosen in accordance with the
positions of the push rods, step cams, and the length of the rocker arms
of the rockers.
The step cams have a number of discrete steps in diameter along their
length, represented by the concentric circles in FIG. 2 and clearly shown
in the plan view of FIG. 4 for step cam 56b. The step cams are moved
transversely across the body of the handle 10 as indicated by the
directional arrow 58. At either end of each step cam is a button, one of
which, 60b, is shown in FIG. 4. As the button 60b is depressed and the
step cam 56b moves upward in the drawing, the rocker arm 54b clicks
smoothly to ride on a decreased diameter of the step cam surface. If
discrete detent settings are not desired the step cam surface could be
made to smoothly vary without steps using, for instance, a threaded
mechanism with a thumbwheel for adjustment. As the rocker arm moves to a
smaller diameter cam surface the rocker 50b pivots to pull the push rod
40b away from the brake pad 146b. The force on spring 48b is decreased,
decreasing the locking force of the brake pad 146b against the lower
pulley 34. As the locking force is decreased the upper knob 24 will turn
more easily to articulate the articulating section of the probe in the
left-right direction.
As the button on the other end of the step cam 56b (not shown in this
drawing) is depressed the braking force against the pulley 34 increases.
At the highest cam surface (greatest diameter) the pulley 34 is firmly
restrained from moving. As discussed in U.S. Pat. No. 5,402,793, this
force can be chosen to firmly retain the articulating section in an
articulated position, but also to be of a low enough force to be overcome
by a forced straightening of the articulating section without injury if
the probe is inadvertently withdrawn from the body in an articulated
position.
In a preferred embodiment, the force required by the user to engage the
articulation brake increases as each successive step of the step cam is
attained. Correspondingly, as the brake is released the rocker arm
cascades continuously and easily to the full brake release setting. This
affords a quick and easy release of the brake in the event of an
emergency.
Each push rod 40a, 40b opposes the arm of a microswitch 62a, 62b. When the
rocker arm of a rocker is riding on the smallest diameter of the step cam
the microswitch for that brake is not actuated. But when the step cam is
moved to begin applying a braking force to a pulley, the arm of the
associated microswitch is moved by the push rod sufficient to close the
microswitch, thereby sending a signal through the cable 16 to the
ultrasound system. A warning is then displayed on the ultrasound system
display, alerting the user that the "ARTICULATION LOCK IS ENGAGED" so that
the user will not inadvertently withdraw the probe from the body of the
patient with the articulating section locked in a curved position. This
further aids in avoiding patient discomfort or injury.
It will be appreciated that other sensors may be employed in place of the
microswitch, such as optical, pressure, or magnetic sensors which will
sense when a braking force is being applied to the articulating mechanism.
It is seen that a sequence of "a" suffix brake elements extend to the right
of the upper pulley 38, ending with the lower step cam 56a.
Correspondingly, the sequence of "b" suffix brake elements extend from the
lower pulley 34 and end at the upper positioned step cam 56b. As a result,
the upper and lower step cams lock the upper and lower articulation
control knobs, respectively. This positional correspondence of the lock
buttons and knobs gives the probe handle an intuitive sense of operation,
which is significant because the user is generally focusing his attention
on the patient or ultrasonic image display while operating the handle
controls by touch.
While the previously described arrangement is seen to be a fully mechanical
implementation it will be appreciated that other implementations such as
electromechanical arrangements are also possible. In place of the step
cams, rockers and push rods one could substitute an electrically
controlled solenoid arrangement, for instance. Other variations will also
be apparent to those skilled in the art.
As previously mentioned, each pulley has two grooves. The articulation
control cable is fastened at one end to ride in one groove. The cable then
extends through the endoscope tube 12 to a point where it is affixed to or
wrapped around a point in the articulating section 30. The cable continues
back through the endoscope tube where it is fastened at the other end to
ride in the other groove of the pulley.
In order to facilitate adjustment of the cable tension a cable adjuster is
inserted in line with the cable just ahead of the pulley. An adjuster 70
is located in line on each side of the cable. One of the adjusters 70a for
the up-down control cable 74 is shown in FIG. 5b, as is one of the
adjusters 72b for the lower, left-right control cable 76. The other two
adjusters (70a', 72b') are on the other side of the handle and are not
visible in this drawing. Each adjuster is comprised of male and female
threaded parts 71 and 73, which screw together to increase the cable
tension and apart to relax the cable tension. The cable length extending
to the articulating section of the probe is connected to the distal
threaded part 71, and the short remaining cable length 74' which leads to
the pulley is connected to the proximal threaded part 73. Just before
engaging the pulley groove the short cable length 74' passes through a
cable guide 80, which guides the cable into the pulley groove.
The cable adjusters serve a dual purpose. In addition to cable tension
adjustment, the adjusters 70 serve as articulation control end stops. The
proximal end of the proximal adjuster part 73 is covered with a polymeric
sleeve 78 which serves as a bumper. As control knob 26 is turned to
articulate the probe by winding cable section 74' onto the pulley 38, the
adjuster 70a and bumper sleeve 78 approach the cable guide 80. The end of
this range of adjustment is reached when the bumper sleeve 78 contacts the
cable guide 80. Thus, an end stop within the handle 10 prevents the
imposition of excessive force on the cable 74 and the articulating section
of the probe.
When the control knob is turned in the other direction, the adjuster 70a'
on the other side of the handle approaches and contacts a cable guide 80'
on the other side of the handle as the short cable section 74' at the
opposite end of the cable is wound onto its pulley groove. The range of
control permitted by the end stops is fixed by the lengths of the
terminating cable sections 74'.
The major lengths 74, 76 of the articulation control cables extend through
the endoscope tube in cable conduits 84, 86, which are preferably spiral
wound conduits formed of wire which is generally square or rectangular in
cross section and may also be squarely wound so that the interior cross
sectional area of the conduit is square or rectangular, which minimizes
friction between the cable and the inner surface of the conduit. Such
conduits are more fully described in U.S. Pat. No. 5,450,851.
In an articulating probe of the present invention it is possible for a
sudden excessive force to be placed upon the articulation control cables
from a variety of causes. One such cause would be dropping the probe so
that it lands on its distal tip, with the force of the fall causing the
articulation section to bend. To guard against the shock of such a sudden
force it is desirable to provide a means for alleviating this sudden force
on the cables. In FIG. 5b the end of each cable conduit is seated in a
sleeve 90, with the terminus of the cable conduit seated against a
narrowing 96 of the internal diameter of the sleeve. The cable 74, 76
passes through the end of the cable conduit and through the proximal
smaller diameter portion 98 of the sleeve. The proximal portion of the
sleeve is fitted into an aperture of a handle member 11 and held in place
by a nut 92 on the threaded proximal end of the sleeve 90. The body of the
sleeve 90 is surrounded by a spring 94 which is retained between the
flanged distal end of the sleeve and the handle member 11.
When a sudden excessive force is applied to the articulating section of the
probe, the force is transmitted to the control cables and their cable
conduits. The force is transmitted through the conduit to the terminus of
the cable conduit, where it is applied to the sleeve 90 at the narrowing
96 of the sleeve. The force will cause the sleeve to be urged in the
proximal direction. As the sleeve 90 moves in this direction the sudden
force is damped by compression of the spring 94, which alleviates the
sudden buildup of force on the articulation mechanism of the probe.
A preferred implementation of the articulation section 30 is shown in FIGS.
7-10. The preferred embodiment is constructed of a series of pivot rings
120, one of which is shown in FIGS. 7a and 7b. The rings are hollow to
permit passage of cables and other connections to the transducer at the
tip of the probe. Around the periphery of each ring are four apertures
100. Each aperture is formed of a conical hole 102 and a semi spherical
depression 104 as shown in FIG. 7a. Apertures which oppose each other
across the ring are paired so that two have the conical hole facing one
direction and the other two are reversed. In FIG. 7b apertures 100 are
paired, as are apertures 100'.
The articulating section 30 is constructed by assembling the pivot rings in
alternating fashion as shown in FIG. 8. The two semi spherical depressions
on one side of a ring oppose two semi spherical depressions on the
opposing ring. A polymeric pivot bead 106 formed of a material such as
nylon with a diametric hole 108 is seated in each set of opposing semi
spherical depressions. The sequence of opposing pivot beads thus
alternates 90.degree. in orientation from one side of each ring to the
other. The cable conduits of each cable are seated in the proximal end
ring 110. The cables exit the conduits and pass through the apertures 100
and pivot bead holes 108 and are terminated at the distal end ring 112.
As the articulating section 30 bends each ring pivots with respect to its
neighbor on a pair of pivot beads 106 as shown in FIG. 8. One set of pivot
beads accommodates bending in one direction (e.g., up-down) and the next
pair of pivot beads accommodates bending in another direction (e.g.,
left-right.) In FIG. 8 the articulating section is bent down by the
tensioning of the lower cable 74.
The conical holes 102 and the pivot beads 106 advantageously accommodate
the bending of the articulating section 30 without allowing the cables to
rub against the pivot rings. This is more clearly shown in the enlarged
view of FIG. 9. There it is seen that the conical shape of the holes 102
provides an expanded opening through which the cables 74 will pass without
contacting the pivot rings regardless of the bending of the articulating
section. The cables extend from the hole 108 of one pivot bead to the next
without any contact with the pivot rings. This permits the articulating
section to bend smoothly and wear longer without fraying of the
articulation control cables.
At the distal end of the articulating section is a housing 114 shown in
FIG. 10 which contains the ultrasonic transducer 130. In a preferred
embodiment the transducer 130 is an array transducer which is affixed in a
rotatable transducer mount 132. The transducer mount rotates on a shaft
134 under control of a drive shaft 136 and gear train. As the user turns
the drive shaft 138 from the control section of the probe, preferably
through control of a motor which turns the drive shaft, the transducer
rotates to change the image plane of the transducer to a new orientation.
The transducer 130 is covered with an acoustic matching layer and an
acoustic lens 160. The acoustic lens may be made of a material such as a
cured RTV compound and provides the transducer with focusing in the
elevational direction. The space 166 around the rotating transducer is
filled with an acoustic coupling fluid and is sealed with a cover 162
which is durable and exhibits the desired acoustic properties. The cover
162 forms the acoustic window through which ultrasonic energy is
transmitted and received by the transducer. Preferably the cover 162 is
acoustically transparent and thin so that it will not cause reverberation
artifacts from the transmitted ultrasonic waves. A sheet of 1.0 mil
Mylar.RTM. has been found to possess the desired properties.
As the transducer 130 rotates, it does so in contact with the cover 162.
Since the space 166 in which the transducer is located is filed with
acoustic fluid, which is often an oil-based compound with lubricating
properties, it would be expected that the transducer surface would rotate
smoothly against the cover, lubricated as it is by the acoustic fluid.
However, the preferred RTV lens material is a non-wetting material, and
has been found to adhere to the Mylar cover even in the presence of the
acoustic fluid. To overcome this problem the transducer and its acoustic
lens are covered with a thin, acoustic membrane 164. A preferred material
for the membrane 164 a polymeric material such as 0.1 mil Mylar, shaped to
the surface shape of the acoustic lens 160. When the acoustic lens 160 is
dome shaped as shown in the drawing, the membrane 164 is also dome shaped
and its shape resembles that of a contact lens. When the membrane 164 is
made of Mylar and the acoustic lens 160 is made of RTV material, the
membrane 164 will stick to the RTV lens and rotate with it. The Mylar lens
will not stick to the Mylar cover 162, however, but rotates smoothly
against it, aided by an intervening thin layer of the acoustic fluid.
Thus, the transducer with its Mylar membrane 164 rotates smoothly against
the cover 162 without binding or sticking.
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